Telescoping piston central lock hydraulic actuator

ABSTRACT

A HYDRAULIC ACTUATOR EMPLOYING TELESCOPING, INDEPENDENTLY MOVABLE OUTER AND INNER PISTONS WITH THE INNER PISTON MOVABLE INDEPENDENTLY TO AN EXTENDED POSITION, WHILE THE OUTER PISTON REMAINS RETRACTED, OR WITH BOTH PISTONS EXTENDED FOR THE MAXIMUM MOVEMENT OF THE OPERATOR WHICH IS MOUNTED ON AND MOVES WITH THE INNER PISTON. BOTH PISTONS ARE SUBSTANTIALLY CYLINDRICAL IN FORM, THE INNER PISTON HAVING LOCKING ELEMENTS CARRIED THEREIN, WHICH ARE MOVABLE RADIALLY WHEN THE PISTONS ARE RETRACTED, FOR EFFECTING LOCKING ENGAGEMENT WITH A STATIONARY PART CARRIED BY THE BODY OF THE ACTUATOR AND RECEIVED WITHIN THE INNER PISTON WHEN IT IS IN RETRACTED POSITION. THE INNER PISTON CARRIES A LOCKING-UNLOCKING PISTON FOR EFFECTING RADIAL MOVEMENTS OF SAID LOCKING ELEMENTS INTO AND OUT OF LOCKING ENGAGEMENT WITH A STATIONARY MEMBER. A PORT IS PROVIDED FOR PRESSURIZING THE INNER PISTON ONLY FOR EXTENSION, A SECOND PORT IS PROVIDED FOR PRESSURIZING THE OUTER PISTON FOR EXTENSION, AND A THIRD PORT IS PROVIDED FOR PRESSURIZING BOTH THE PISTONS FOR RETRACTING MOVEMENT THEREOF.

D. L. NEPP TELESCOPING PISTON, CENTRAL LOCK HYDRAULIC ACTUATOR Filed Sept.' 29

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@d0 2 Wl TELESCOPING` PISTON, CENTRAL LOCK HYDRAULIC ACTUATOR Filed sept. 29. 1969 2 Sheets-Sheet mw A ww wm INVUN'IUR. 00A/a0 Z, NEA@ B Y M, mj M4,

o@ /a/na ,47m/@wf s45 3,l4,9.l2 Patented Oct. 26, 1971 3,614,912 TELESCOPING PISTON, CENTRAL LUCK HYDRAULIC ACTUATUR Donald L. Nepp, San Pedro, Calif., assiguor t Lionel Pacific, Inc., Anaheim, Calif. Filed Sept. 29, 1969, Ser. No. 361,563 int. Cl. FlSb /26 lU.S. Cl. 92-25 8 Claims ABSTRACT OF THE DISCLOSURE A hydraulic actuator employing telescoping, independently movable outer and inner pistons with the inner piston movable independently to an extended position, while the outer piston remains retracted, or with both pistons extended for the maximum movement of the operator which is mounted on and moves with the inner piston. Both pistons are substantially cylindrical in form, the inner piston having locking elements carried therein, which are movable radially when the pistons are retracted, for effecting locking engagement with a stationary part carried by the body of the actuator and received within the inner piston when it is in retracted position. The inner piston carries a locking-unlocking piston for effecting radial movements of said locking elements into and out of locking engagement with a stationary member. A port is provided for pressurizing the inner piston only for extension, a second port is provided for pressurizing the outer piston for extension, and a third port is provided for pressurizing both the pistons for retracting movement thereof.

SUMMARY OF THE INVENTION A hydraulic actuator including a body portion providing a hydraulic cylinder in which reciprocates an outer piston, the cylinder having a rst extension port and a retraction port for effecting extension and retraction movements of said outer piston, the extension pressure acting on substatially the entire area of the outer piston, while the retraction pressure acts on an outer annulus provided between the body of the outer piston and the cylinder wall.

The outer piston is cylindrical in form and has a cylindrical barrel thereinside in which slides an independently movable inner piston acted upon by extension pressure from a second extension pressure port applied over substantial-ly the entire area of the inner piston, to elfect extension thereof. The inner piston is also pressurized from the retraction port, along the barrel in the outer piston, applied to an annulus provided between the outer diameter of the inner piston and the inner diameter of the barrel to effect retraction movement of the inner piston.

The inner piston is cylindrical in form and has rigidly secured thereto and carried interiorly thereof a locking cylinder having a locking piston movable therein. The locking piston is biased toward locking position and is movable to unlocking position by extension pressure on the inner piston. The locking cylinder has radial slots therein through which project locking elements movable by the locking piston into locking position, and collapsible to unlocking positions upon pressurized movement of the locking piston. A spring-biased sleeve is carried exteriorly of the locking cylinder and moves over the locking elements to retain them inwardly when the inner piston starts its extension movement. A locking member is carried by the actuator body in stationary relationship thereto, said locking member having a locking head receiveable in the inner piston and providing an end ange engageable by said locking elements when extended in locking position, the locking piston moving the locking elements into locking position under its spring bias.

It is therefore an object of the invention to provide an improved hydraulic actuator employing telescoping pistons to secure a large operator movement relative to the longitudinal dimension of the actuator, and minimizing the transverse actuator dimension by locating the retractable locking elements centrally within the inner piston.

A further object of the invention is to provide a hydraulic actuator, as defined in the preceding object, in which the locking elements are radially movable and carried by the inner piston, being movable radially outwardly into locking engagement with a stationary Ilocking head mounted in the actuator body and received within the inner piston so as to be engageable by the locking elements therein.

More specifically, it is a further object of the invention to provide toggle links engageable with the locking elements and carried by a locking piston which moves relative to the inner piston to rotate the toggle links and effect radial movements of the locking elements into and out of locking position.

Other objects and features of the invention will be apparent from the detailed description.

BRIEF DESCRIPTION OF THE DRAWING FIG. l is a longitudinal sectional View through the hydraulic actuator according to the present invention;

FIG. 2 is a partial, enlarged detail View of the locking mechanism in locked position;

FIG. 3 is a transverse sectional view on the line 3 3 of FIG. 2, and

FIG. 4 is a longitudinal sectional view in two parts showing the actuator in fully extended position.

DETAILED DESCRIPTION The hydraulic actuator 11 according to the present invention is exemplified in a barrel-like body portion 12 providing an operating chamber 13 closed at its back end by an integral end cap 14 having a transverse opening therethrough receiving a pin 15 about which the actuator is pivoted on a fixed part 16. Rigidly secured in the end cap 14 is a tubular locking member 17 having a bore 18 therethrough. The member 17 is sealed in its end cap socket at 19, and its bore 18 is connected by a passage 21 to an unlocking and inner piston extending pressurizing port 22. The tubular member 17 is held in place by a shaped washer 23 and an annular nut 24. The back of the chamber 13 is connected by a passage 2S to an outer piston extending pressurizing port 26. The locking member 17 has ports 27 therethrough adjacent its forward end where it terminates in a cup-shaped locking head 28. The locking head 28 has an annular end flange 29 having a beveled locking surface interiorly thereof with which the locking elements (to be described) cooperate.

Mounted within the chamber 13 is an outer operating piston 31 sealed to the cylinder wall at 32, threaded together at 33 to enclose an interior barrel 34 therein slightly spaced from the interior wall of the cylindrical outer piston 31. The outer portion is sealed to members 17 at 30. The inner barrel 34 is sealed to the outer piston at 35 and has end ports 36 therethrough communicating along the length of the barrel 34 in the space between its outer surface and the inner surface of the outer piston and through a port 37 through the outer piston with a retraction pressure port 38 connected by a passage 39 to the forward end of the cylinder 13. The forward end of the body portion 12 of the actuator receives a pair of annular nuts 41, 42 through which the outer piston 31 is slidably supported and which carry a seal 43 therefor. The nut 41 is sealed to the main body of the actuator at 44.

Within the inner barrel 34, exteriorly of the locking member 17 and head 28, is a generally cylindrical piston 45 sealed to the barrel 34 at 46 on its interior end to the outer piston 31 and at 47 on its forward end. An annular nut 48 maintains the seal 47. The inner cylindrical piston 45 has a thickened head portion 49 in the exterior end of which is threaded the stem 51 of an operator 52 an eye connected by a pin 53 to an operated part 54. Interiorly of the head 49 is threaded a locking cylinder 55 sealed thereto at 56. The locking cylinder 55 provides a chamber 57 within which reciprocates a locking piston 58 biased outwardly toward its locking position by a spring 59 in the chamber 57. The piston 58 is sealed in the chamber 57 at 61 and is movable toward the left, as viewed in FIG. 1, into the unlocking position of FIG. 4 by means of unlocking pressure from the port 22 passing through the bore 1S of the locking member 17.

The locking cylinder S5 has opposed, radially directed slots 62 adjacent its interior end through which extend radially reciprocable locking elements 63, movable into and out of engagement with the flange 29 on the head 28, the parts being shown in FIGS. 1-3 in retracted, locked position. Upon the locking piston 58 are pivotally mounted toggle links 64, as by a pin 65. The free ends of the toggle links 64 engage in grooves in the locking elements 63, so as to be rotatable relative thereto from the position of FIGS. 1 3 to the collapsed position of FIG. 4, the toggle movement in the collapsing direction permitting the locking element 63 to move radially inwardly, thus unlatching the beveled surface of the flange 29 on the head 28.

Mounted on the exterior of the locking cylinder 55 in sliding relation is a sleeve 66 biased rearwardly by a spring 67 and engageable with the end of the locking head 28 to be held in the retracted position of FIGS. 1 and 2. As the locking cylinder 55 moves forwardly away from the head 28, the sleeve moves rearwardly over the locking elements 63 to hold them in retracted position, as shown in FIG. 4.

The operation of the actuator of this invention is as follows:

The parts are shown in FIGS. 1-3 in retracted, locked position. Unlocking pressure is first applied to the port 22 while the port 38 is connected to reservoir, as may also be port 26. Pressure from the port 22 passes through passage 21 and bore 18 to the locking piston 58 where it is effective over the major diameter of the seal 61. This acts against the bias of spring 59 to move the locking piston 5S to the left, as viewed in FIG. l, into substantially the position of FIG. 4, permitting the locking elements 63 to be retracted out of engagement with the beveled surface of the flange 29 on the locking head 28. The unlocking pressure passes freely through ports 27 to be applied to the entire diameter of the inner piston 45 which now extends to the left, as viewed in FIG. 1, until it assumes the position of FIG. 4, except that the outer piston 31 remains retracted because of the unlocking pressure applied to the inner end area of the outer piston.

Motion may be terminated at this point with only the inner piston extended if sufficient movement of the operator 52 is attained thereby. However, if full extension is desired, the port 26 is now connected to extension pressure which is appied over the entire outer end area of the piston 31 to effect extension thereof into the double piston extended arrangement of FIG. 4.

Alternatively, the port 26 can be pressurized at the same time port 22 is pressurized, whereupon both pistons move at the same time in an extending direction into the position of FIG. 4.

As locking member 55 leaves the locking head 28, the sleeve 66 moves rearwardly over the locking element 63, as in FIG. 4, to prevent their moving outwardly.

To retract both pistons, the port 3S is pressurized, while the ports 22 and 26 are connected to reservoir. Retracting pressure is applied to the main piston 31 about the annulus provided in the chamber 13 between the surface thereof and the exterior surface of the outer piston. This moves the outer piston in a retracting direction. Retracting pressure from the port 38 also passes through port 37 4 along the barrel 34 and through port 36 to the exterior of the inner piston 45 where it acts on the annulus between the outer surface of the inner piston and the inner surface of the barrel 34 to move the inner piston 45 in a retracting direction.

Just prior to reaching the position of FIGS. 1 and 2, the end of locking head 28 engages the sleeve 66 to move it against its spring 67 into the position of FIGS. l and 2, at which time the locking elements 63 are snapped behind the flange 29 on the head 28 by the action of spring 59, thereby locking the parts in retracted position against movement of the operator 52 until unlocking pressure is applied to the port 22, as first described above. It is to be understood that all areas and volumes between seals will be at the same operating pressure, whether or not specific ports and passages are illustrated.

While a certain preferred embodiment of the invention has been specifically illustrated and described, it will be understood that the invention is not limited thereto, as many variations will be apparent to those skilled in the art.

I claim:

l. A hydraulic actuator comprising:

a body portion providing an operating chamber;

a substantially cylindrical outer piston mounted in said chamber for extending and retracting movements therein;

a substantially cylindrical inner piston mounted in said outer piston for extending and retracting movements relative thereto;

a movable locking member mounted in said inner piston for movement therewith;

a stationary locking member carried by said body portion and receivable in said inner piston when it is in its retracted position;

radially moavble locking elements carried by one of said members;

a locking piston carried by said one member for moving said locking elements into locking position;

biasing means moving said locking piston into locking position where it moves said radially movable locking elements into locking engagement with the other of said members;

means for applying pressure to said locking piston to effect movement thereof against its bias to provide for movement of said locking elements into unlocking position, said means for pressurizing said locking piston also simultaneously pressurizing said inner piston for movement thereof in an extending direction after said locking piston has been moved to unlocking position; and

means for applying extending pressure to said outer piston to effect further movement of said inner piston therewith beyond the individually extended position of said inner piston.

2. The hydraulic actuator dened in claim 1 and comprising:

said radially movable locking elements being disposed in substantially radial slots in said movable locking member and moving outwardly into locking engagement with said stationary member; and

said locking piston also being carried by said movable locking member and having therein said biasing means for moving said locking elements into locking position.

3. The hydraulic actuator defined in claim 2 including:

toggle links carried by said locking piston and engaging in said radially movable locking elements to effect locking and unlocking movements of said locking elements as the locking piston moves said toggle links toward extended and collapsed positions.

4. The hydraulic actuator of claim 3, and including:

a cylindrical barrel between said inner and outer pistons and sealed thereto and providing a restricted passage between the inner surface of the outer piston and the outer surface of the barrel for the transmittal of retracting pressure to the exterior of said inner piston to efrect movement thereof in a retracting direction. 5. The hydraulic actuator defined in claim 1, and comprising:

means for applying retracting pressure to both said inner and outer pistons while the extending pressurizing means is inoperative, whereby to eiect retractin-g movement of both said pistons into said operating chamber; and

means operative when said inner piston is in its retracted position for effecting movement of said locking piston and said radially movable locking elements into locking engagement with said other member.

6. The hydraulic actuator dened in claim 1 including:

a sleeve mounted over said one member; and

biasing means for said sleeve for moving it over said locking elements when they are in unlocking position to prevent locking movement thereof;

said other member engaging said sleeve as said inner piston moves into retracted position whereby to uncover said locking elements for movement into locking position.

7. The hydraulic actuator of claim 1, and including:

a cylindrical barrel between said inner and outer pistons and sealed thereto and providing a restricted passage between the inner surface of the outer piston and the outer surface of the barrel for the transmittal of retracting pressure to the exterior of said inner piston to eiTect movement thereof in a retracting direction.

8. A hydraulic actuator comprising:

a body portion providing an operating chamber;

a substantially cylindrical outer piston mounted in said chamber for extending and retracting movements therein;

a substantially cylindrical inner piston mounted in said outer piston for extending and retracting movements relative thereto;

a movable locking member mounted in said inner piston for movement therewith;

a stationary locking member carried by said body portion and receivable in said inner piston when it is in its retracted position;

radially movable locking elements carried by one of said members;

a locking piston carried by said one member for moving said locking elements into locking position; and

a cylindrical barrel between said inner and outer pistons and sealed thereto and providing a restricted passage between the inner surface of the outer piston and the outer surface of the barrel for the transmittal of retracting pressure to the exterior of said inner piston to effect movement thereof in a retracting direction.

References Cited UNITED STATES PATENTS 5/1959 Brady 92-51 2/ 1962 Chase 92-25 U.S. Cl. X.R.

STANES PATENT OFFCE 35@ UMTEE n Cmnrmwr of? mm1-mmm Patent No. i 3,614,912 l Dated october 26, 1971 Invencor) NEPP, DONALD L.

1t is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected es shown below:

Column l, line E,`

Column 3, line 3Y Column 4, line 36k,

after"'operetor 52," i

after l "radially". delete f'moavble" and insert .therefor` --morvlable-r.

Signed and sealed `this 2nd eeyl of Mey 'l SEAL Attest:

EDWARI) M.FLETCHER,JR. attesi-,ing Officer ROBERT GOTTSCHALK Commissioner Vo1? Patents 

